GB663519A - Gas-tight containers and method of packaging - Google Patents

Abstract

663,519. Packing. BERGSTEIN, S. Oct. 3, 1947, No. 26714/47. Class 94(i). A gas-tight protective package comprises a substantially tubular gas-tight sleeve secured around the body portion of a container, the sleeve being seamed to itself in a gas-tight manner, and the container having end closures comprising sealing material which extends to cover at least the ends of the sleeve. The sleeve may be formed from transparent, non-fibrous film secured to the body walls of a flexible container by means of a translucent thermoplastic substance. In one example a paperboard carton blank is provided with a sleeve of cellulose acetate or ethyl cellulose. Sleeves of metal foil laminated to sheets of glassine or film may also be used. In Fig. 2 knocked down cartons 13 are shown stacked in a hopper 14 and are fed forward singly by means of a feeder device 15. A sheet 17 of sleeve material is positioned upon a divided table 16 and is carried by the downwardly fed carton between electrically heated pressure rollers 20 and 21 which serve to fold the sheet 17 about the body walls of the carton and affix it thereto. The sheet is preferably coated with thermoplastic adhesive though the latter may be applied to the carton instead. The partly wrapped carton is swung to the dotted line horizontal position by a moving finger 23 and comes to rest on a conveyor 24. During this movement a projecting part 25 of the sleeve is folded back by means of a folder 26 and the conveyor 24 moves the carton into the bite of another pair of heated rolls 27, 28 so as to seal the overlapped ends of the sleeveforming material and form a gas-tight longitudinal seam. The carton is then erected, filled and closed at its ends in the usual manner and end seals may be formed by merely dipping the end portions into a bath of sealing substance. End seals are preferably formed however by means of a moulding device comprising a main platform member 33 shaped to conform to the end of the package and having hinged end elements 35, 37 and hinged side elements (not seen in Fig. 6). A cap sheet, Fig. 5 (not shown), is placed on the platform 33 and after dipping the end portion of the carton into a bath of sealing substance so as to coat the carton end and contiguous parts of the sleeve, the end of the carton is placed on the platform 33 and pressed downwardly against the action of springs 41, 42. The hinged moulding elements 35, 37 &c., are swung upwardly by a series of pins 43, 44 and thus fold the cap sheet about the end of the package to form a gas-tight seal. In modifications the closures may be moulded to greater thicknesses about the edges and corners of the carton by suitably shaping the moulding elements. Also instead of dipping the carton ends, the cap sheet may be formed into the shape of a pan on the moulding device, on to which a quantity of liquified sealing material may be poured. Alternatively, cap sheets previously thickly coated with thermoplastic sealing material may be used. The sealed package is then punctured for gassing purposes and this may be done by placing the container in a chamber which is evacuated and then filled with the gas which it is desired to introduce into the containers. A preferred method is to use apparatus shown in Fig. 9, comprising a pair of spaced hollow needles 52, 53 one of which is longer than the other and connected to a gas tank 55. The two needles are mounted on a support 51 which is brought down to the dotted line position so as to cause the needles to puncture the sleeve at the positions of holes or tabs previously cut in the carton blank. After displacing the air in the carton 50 with gas the needles are withdrawn and the punctures formed thereby are sealed either by adhesively securing portions of sleeve forming material over them or by means of a deposited seal of thermoplastic material. The Specification as open to inspection under Sect. 91 comprises also the following modifications. Instead of a paperboard carton, a paperboard sleeve without end flaps may be used. Alternatively, the carton may be dispensed with, the gas-tight sleeve being formed and one end folded about a mandrel or interior platform which is used to sustain the pressure of the platform 33 and elements 35, 37 &c. during the moulding of the end closures. The sleeve is then filled with the desired contents and a similar closure is formed at the other end using the contents or an interior platform for support. As a further alternative the sleeve may take the form of a bag closed at one end. This subject-matter does not appear in the Specification as accepted.